Integrin-α FG-GAP repeat-containing protein 2 is critical for normal B cell differentiation and controls disease development in a lupus model

Genomic and biogeographic characterisation of the novel prasinovirus Mantoniella tinhauana virus 1

Mamiellophyceae are a ubiquitous class of unicellular green algae in the global ocean. Their ecological importance is highlighted in studies focused on the prominent genera Micromonas, Ostreococcus, and Bathycoccus. Mamiellophyceae are susceptible to prasinoviruses, double-stranded DNA viruses belonging to the nucleocytoplasmic large DNA virus group. Our study represents the first isolation of a prasinovirus in the South China Sea and the only one to infect the globally distributed genus Mantoniella. We conducted a comparative analysis with previously identified viral relatives, encompassing morphological characteristics, host specificity, marker-based phylogenetic placement, and whole-genome sequence comparisons. Although it shares morphological and genetic similarities with established prasinoviruses, this novel virus showed distinct genetic traits, confining its infection to the species Mantoniella tinhauana. We also explored the global biogeography of this prasinovirus and its host by mapping metagenomic data and analysing their relationship with various environmental parameters. Our results demonstrate a pronounced link between the virus and its host, both found predominantly in higher latitudes in the surface ocean. By gaining an increased understanding of the relationships between viruses, hosts, and environments, researchers can better make predictions and potentially implement measures to mitigate the consequences of climate change on oceanic processes.

A novel surface marker CD49d promotes TNF expression in oyster agranulocytes by mediating the MAPK pathway

CD49d, encoded by the gene Integrin α4, is a significant member of cell adhesion receptors, which is widely expressed in various immune cells to trigger immune responses against invading pathogens. In the present study, the expression of CgCD49d and its regulatory role in TNF expression were investigated in the Pacific oyster Crassostrea gigas. There were five Int-alpha domains, an Integrin_alpha2 region and a unique FG-GAP repeat region inserted identified in CgCD49d. CgCD49d transcript was specifically expressed in haemocytes, and its mRNA expression level in haemocytes increased after LPS and Vibrio splendidus stimulation. After CgCD49d was blocked by using its antibody, the phosphorylation level of CgJNK in the MAPK signaling pathway and CgTNF transcripts decreased significantly post V. splendidus stimulation. After phosphorylation level of CgJNK was inhibited by using its inhibitor, the nuclear translocation of CgRel was restrained and CgTNF transcripts also decreased significantly post V. splendidus stimulation. Furthermore, CgCD49d was found to be mainly expressed in the agranulocyte subpopulation, and Alexa Fluor 488-conjugated CgCD49d antibody labeled agranulocytes with a circle of green fluorescence signals on CgCD49d+ agranulocyte surface under Confocal microscopy, which accounted for 24.9 ± 4.53% of total haemocytes. Collectively, these results suggested that CgCD49d promoted TNF expression in oyster haemocytes against bacterial invasion by mediating MAPK pathway, and it could be used as a surface marker to type and sort a subset of agranulocyte subpopulation among haemocytes.

ITFG2, an immune-modulatory protein, targets ATP 5b to maintain mitochondrial function in myocardial infarction

ITFG2, as an immune-modulatory intracellular protein that modulate the fate of B cells and negatively regulates mTORC1 signaling. ITFG2 is highly expressed in the heart, but its pathophysiological function in heart disease is unclear. In this study, we found that in MI mice, overexpression of ITFG2 via an AAV9 vector significantly reduced the infarct size and ameliorated cardiac function. Knockdown of endogenous ITFG2 by shRNA partially aggravated ischemia-induced cardiac dysfunction. In cardiac-specific ITFG2 transgenic (TG) mice, myocardial infarction size was smaller, eject fraction (EF) and fractional shortening (FS) was higher compared to those in wild-type (WT) mice, suggesting ITFG2 reversed cardiac dysfunction induced by MI. In hypoxic neonatal cardiomyocytes (NMCMs), overexpression of ITFG2 maintained mitochondrial function by increasing intracellular ATP production, reducing ROS levels, and preserving the mitochondrial membrane potential (MMP). Overexpression of ITFG2 reversed the mitochondrial respiratory dysfunction in NMCMs induced by hypoxia. Knockdown of endogenous ITFG2 by siRNA did the opposite. Mechanism, ITFG2 formed a complex with NEDD4-2 and ATP 5b and inhibited the binding of NEDD4-2 with ATP 5b leading to the reduction ubiquitination of ATP 5b. Our findings reveal a previously unknown ability of ITFG2 to protect the heart against ischemic injury by interacting with ATP 5b and thereby regulating mitochondrial function. ITFG2 has promise as a novel strategy for the clinical management of MI.

Longitudinal changes in DNA methylation during the onset of islet autoimmunity differentiate between reversion versus progression of islet autoimmunity

Background

Type 1 diabetes (T1D) is preceded by a heterogenous pre-clinical phase, islet autoimmunity (IA). We aimed to identify pre vs. post-IA seroconversion (SV) changes in DNAm that differed across three IA progression phenotypes, those who lose autoantibodies (reverters), progress to clinical T1D (progressors), or maintain autoantibody levels (maintainers).

Methods

This epigenome-wide association study (EWAS) included longitudinal DNAm measurements in blood (Illumina 450K and EPIC) from participants in Diabetes Autoimmunity Study in the Young (DAISY) who developed IA, one or more islet autoantibodies on at least two consecutive visits. We compared reverters - individuals who sero-reverted, negative for all autoantibodies on at least two consecutive visits and did not develop T1D (n=41); maintainers - continued to test positive for autoantibodies but did not develop T1D (n=60); progressors - developed clinical T1D (n=42). DNAm data were measured before (pre-SV visit) and after IA (post-SV visit). Linear mixed models were used to test for differences in pre- vs post-SV changes in DNAm across the three groups. Linear mixed models were also used to test for group differences in average DNAm. Cell proportions, age, and sex were adjusted for in all models. Median follow-up across all participants was 15.5 yrs. (interquartile range (IQR): 10.8-18.7).

Results

The median age at the pre-SV visit was 2.2 yrs. (IQR: 0.8-5.3) in progressors, compared to 6.0 yrs. (IQR: 1.3-8.4) in reverters, and 5.7 yrs. (IQR: 1.4-9.7) in maintainers. Median time between the visits was similar in reverters 1.4 yrs. (IQR: 1-1.9), maintainers 1.3 yrs. (IQR: 1.0-2.0), and progressors 1.8 yrs. (IQR: 1.0-2.0). Changes in DNAm, pre- vs post-SV, differed across the groups at one site (cg16066195) and 11 regions. Average DNAm (mean of pre- and post-SV) differed across 22 regions.

Conclusion

Differentially changing DNAm regions were located in genomic areas related to beta cell function, immune cell differentiation, and immune cell function.

Plasmodium berghei-Released Factor, PbTIP, Modulates the Host Innate Immune Responses

The Plasmodium parasite has to cross various immunological barriers for successful infection. Parasites have evolved mechanisms to evade host immune responses, which hugely contributes to the successful infection and transmission by parasites. One way in which a parasite evades immune surveillance is by expressing molecular mimics of the host molecules in order to manipulate the host responses. In this study, we report a Plasmodium berghei hypothetical protein, PbTIP (PbANKA_124360.0), which is a Plasmodium homolog of the human T-cell immunomodulatory protein (TIP). The latter possesses immunomodulatory activities and suppressed the host immune responses in a mouse acute graft-versus-host disease (GvHD) model. The Plasmodium berghei protein, PbTIP, is expressed on the merozoite surface and exported to the host erythrocyte surface upon infection. It is shed in the blood circulation by the activity of an uncharacterized membrane protease(s). The shed PbTIP could be detected in the host serum during infection. Our results demonstrate that the shed PbTIP exhibits binding on the surface of macrophages and reduces their inflammatory cytokine response while upregulating the anti-inflammatory cytokines such as TGF-β and IL-10. Such manipulated immune responses are observed in the later stage of malaria infection. PbTIP induced Th2-type gene transcript changes in macrophages, hinting toward its potential to regulate the host immune responses against the parasite. Therefore, this study highlights the role of a Plasmodium-released protein, PbTIP, in immune evasion using macrophages, which may represent the critical strategy of the parasite to successfully survive and thrive in its host. This study also indicates the human malaria parasite TIP as a potential diagnostic molecule that could be exploited in lateral flow-based immunochromatographic tests for malaria disease diagnosis.

Defective Pollen Wall 3 (DPW3), a novel alpha integrin-like protein, is required for pollen wall formation in rice

In flowering plants, pollen wall is a specialized extracellular cell-wall matrix surrounding male gametophytes and acts as a natural protector of pollen grains against various environmental and biological stresses. The formation of pollen wall is a complex but well-regulated process, which involves the action of many different genes. However, the genetic and molecular mechanisms underlying this process remain largely unknown. In this study, we isolated and characterized a novel rice male sterile mutant, defective pollen wall3 (dpw3), which displays smaller and paler anthers with aborted pollen grains. DPW3 encodes a novel membrane-associated alpha integrin-like protein conserved in land plants. DPW3 is ubiquitously expressed in anther developmental stages and its protein is localized to the plasma membrane, endoplasmic reticulum (ER) and Golgi. Anthers of dpw3 plants exhibited unbalanced anther cuticular profile, abnormal Ubisch bodies, disrupted callose deposition, defective pollen wall formation such as abnormal microspore plasma membrane undulation and defective primexine formation, resulting in pollen abortion and complete male sterility. Our findings revealed a novel and vital role of alpha integrin-like proteins in plant male reproduction.

Preliminary evaluation of a Trypanosoma brucei FG-GAP repeat containing protein of mitochondrial localization

Background: Trypanosoma brucei, a causative agent of African Trypanosomiasis, is known to cross the blood brain barrier during the second stage of the disease. It was previously suggested that this parasite crosses the blood brain barrier in a manner similar to that of lymphocytes. This would imply that trypanosomes possess integrins that are required to interact with adhesion molecules located on the blood brain barrier microvascular endothelial cells, as a first step in traversal. To date, no T. brucei integrin has been described. However, one T. brucei putative FG-GAP repeat containing protein (typical of integrins) encoded by the Tb927.11.720 gene, was predicted to be involved in cell-cell/cell-matrix adhesion. Therefore, this study sought to characterize a putative FG-GAP repeat containing protein (FG-GAP RCP) and to determine its cellular localization as a basis for further exploration of its potential role in cell-cell or cell-matrix adhesion. Methods: In this study, we successfully cloned, characterized, expressed and localized this protein using antibodies we produced against its VCBS domain in T. brucei. Results: Contrary to what we initially suspected, our data showed that this protein is localized to the mitochondria but not the plasma membrane. Our data showed that it contains putative calcium binding motifs within the FG-GAP repeats suggesting it could be involved in calcium signaling/binding in the mitochondrion of T. brucei. Conclusion: Based on its localization we conclude that this protein is unlikely to be a trypanosomal integrin and thus that it may not be involved in traversal of the blood brain barrier. However, it could be involved in calcium signaling in the mitochondrion.

Predicting human disease mutations and identifying drug targets from mouse gene knockout phenotyping campaigns

Two large-scale mouse gene knockout phenotyping campaigns have provided extensive data on the functions of thousands of mammalian genes. The ongoing International Mouse Phenotyping Consortium (IMPC), with the goal of examining all ∼20,000 mouse genes, has examined 5115 genes since 2011, and phenotypic data from several analyses are available on the IMPC website (www.mousephenotype.org). Mutant mice having at least one human genetic disease-associated phenotype are available for 185 IMPC genes. Lexicon Pharmaceuticals' Genome5000™ campaign performed similar analyses between 2000 and the end of 2008 focusing on the druggable genome, including enzymes, receptors, transporters, channels and secreted proteins. Mutants (4654 genes, with 3762 viable adult homozygous lines) with therapeutically interesting phenotypes were studied extensively. Importantly, phenotypes for 29 Lexicon mouse gene knockouts were published prior to observations of similar phenotypes resulting from homologous mutations in human genetic disorders. Knockout mouse phenotypes for an additional 30 genes mimicked previously published human genetic disorders. Several of these models have helped develop effective treatments for human diseases. For example, studying Tph1 knockout mice (lacking peripheral serotonin) aided the development of telotristat ethyl, an approved treatment for carcinoid syndrome. Sglt1 (also known as Slc5a1) and Sglt2 (also known as Slc5a2) knockout mice were employed to develop sotagliflozin, a dual SGLT1/SGLT2 inhibitor having success in clinical trials for diabetes. Clinical trials evaluating inhibitors of AAK1 (neuropathic pain) and SGLT1 (diabetes) are underway. The research community can take advantage of these unbiased analyses of gene function in mice, including the minimally studied 'ignorome' genes.